Review of the 1755 Lisbon Earthquake Based on Recent Analyses of Historical Observations - Historical Seismology: Interdisciplinary Studies of Past and Recent Earthquakes - page 262

Epicenter of the Gorringe Bank earthquake of February 28, 1969 (Martinez Solarez et al .,1979)
and the possible source of the 1755 earthquake
Estimated epicenter of the 1755 earthquake (Udias etal ., 1976)
Possible epicentral zone of the 1755 earthquake (Mendes et al ., 1999)
Fig. 1 Map of isoseismals (MSK Intensities) from the earthquake of November 1st 1755, with
some possible localizations of the seismic source (based on Martinez Solares et al. (1979); Levret
(1991); Moreira (1984) and Mendes et al. (1999)
we should mention Choffat (1904), Reid (1914), Pereira de Sousa (1919-1932),
Moreira (1984) and Martinez-Solares (1979). Figures 1 and 2 summarize some of
those studies, presenting the isoseismals and the possible localizations of epicentres
of 1755 and of February/28/1969 event, which, until a few years ago, was considered
as belonging to the same geo-morphological fault system.
The analysis of the isoseismals in Fig. 2, which joins large consensus among
specialists, shows clearly that the vibrations were more intense in the south of the
Mainland and in the area of Lisbon, attenuating rapidly from coastal line of the
country both in the west and south. The geometric pattern of the attenuation is
clearly away from the typical patterns of other earthquakes where the attenuation